Fluid tilt sensor within ink tank supply item for micro-fluid applications

ABSTRACT

A container for holding a volume of fluid and having a housing defining an interior for retaining the volume of fluid; at least one in-tank tilt sensor connected to a controller and disposed inside the housing for generating a signal corresponding to a level of fluid inside the housing; and a support material attached to the housing and connected to the at least one in-tank tilt sensor to mechanically support the at least one in-tank tilt sensor such that the at least one in-tank tilt sensor is not in direct contact with the fluid inside the housing. The in-tank tilt sensor detects a change in fluid level which may only be caused by tilting of the imaging device. When tilting is registered, protective action is taken to prevent fluid from leaking.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to micro-fluid applications,such as inkjet printing. The present disclosure relates particularly toa fluid container that senses tilting during such application. Tiltingis determined based on capacitive sensing by in-tank tilt sensors.

BACKGROUND

The art of printing images with micro-fluid technology is relativelywell-known. A permanent or semi-permanent printhead has access to alocal or remote supply of fluid. The fluid is usually stored in acontainer, such as a tank or a cartridge. In an imaging device having alocal supply of fluid, the container is installed within the housing ofthe imaging device. The fluid ejects from the printhead nozzles to aprint media in a pattern of pixels corresponding to images beingprinted.

During printing, the printhead maintains a backpressure so that fluidcannot leak out of the printhead nozzles. Hence, tilting an imagingdevice having a local supply of fluid may cause serious issues. This ismost commonly a problem for imaging devices which rely on the differencein the height of the printhead and the fluid container for setting thebackpressure of the printhead.

Knowing whether or not an imaging device is tilted lends itself to avariety of consumer features. Imaging devices can warn users that theimaging device is tilted. Also, an operation of the imaging device maybe suspended if the imaging device is tilted in order to avoid fluidspillage. Users may also be advised to perform corrective measures.

Manufacturers have implemented a variety of container tilt measurementsystems and techniques. Each has its own set of advantages and problems.Some are cheap while others are costly. Some work as intended whileothers have proven so poorly that users regularly ignore them. Stillothers are complex, including complicated processing, algorithms. Theoptimum balance is to provide accurate tilt measurement over a lifetimeof a fluid container, but without adding complexity or cost.

One existing method for detecting tilting is to install a traditionalelectrical tilt sensor on the imaging device's circuit board. When thissensor detects that the imaging device is tilted, the firmware closes afluidic valve between the printhead and the fluid container in order toprevent the fluid from leaking out of the printhead nozzles. A dedicatedelectrical tilt sensor increases the cost of the imaging device.

Accordingly, a need exists in the art for an alternative method fordetecting tilt in the imaging device.

SUMMARY

The above-mentioned and other problems become solved with capacitivetilt detection system utilizing existing sensors that an imaging deviceuses in detecting the level of fluid in a fluid container.

The basic concept of capacitive tilt detection is a method by which apair of metal plates or electrodes are placed on the fluid container toconstitute a capacitive in-tank sensor with one electrode being used inconjunction with a transmit circuit, and the other being used as areceiver. In imaging devices which use capacitive in-tank sensors tomeasure the level of fluid inside the container, the same sensors may beutilized to determine tilting of the container. Utilizing the samesensors to determine the level of fluid and to determine tilting of thecontainer lowers the manufacturing cost.

Upon application of electrical energy, circuitry measures capacitance ofthe fluid residing in the space between the capacitive electrodes. Whenthe transmit electrode is stimulated, the receiver electrode andcircuitry measures the capacitance of the fluid residing in the spacebetween the capacitive electrodes. The capacitance varies according tothe volume of fluid residing in the space between the capacitiveelectrodes. The volume of fluid between the capacitive electrodeschanges as the level of fluid between the capacitive electrodes changes.This method of using capacitive electrodes in detecting tilting of thecontainer has several benefits inherent to it, including that no probeor other sensor intrusion into the tank is needed to measurecapacitance, no clear window is needed for optical sensing at eachlevel, and the same pair of capacitive electrodes used in ink leveldetection provides the capacitance readings to be used in detectingtilting during the lifetime of the fluid container.

The present disclosure uses the concept and process by which capacitiveelectrodes are used to detect titling of a fluid container or ink tank,and to take the appropriate precautions to prevent the imaging devicefrom possibly leaking fluid, such as by closing a valve to prevent fluidfrom flowing to the printhead. The present disclosure operates to detecttilt by measuring changes in fluid level which are caused by tilting ofthe fluid container.

In a representative embodiment, a container for an imaging device holdsa volume of fluid. Its housing defines an interior and a fluid exit port(not shown). A pair of metal plates or electrodes is disposed on thehousing. These metal plates function as capacitive electrodes andmeasure the capacitance of the volume of fluid between the capacitiveelectrodes. The capacitance reading is in proportion to the volume offluid between the capacitive electrodes but not necessarily to theentire volume of fluid inside the container. Even with a constant volumeof fluid, the capacitance readings provided by the capacitive electrodesmay vary if the container is tilted towards various directions atvarying extent. Changes in the volume of fluid between the capacitiveelectrodes equate to changes in the capacitance readings. When thecontainer is not tilted, the capacitance reading provided by thecapacitive electrodes may be used as a reference capacitance during tiltdetection. For example, when the same container with the same volume offluid is tilted towards the location of the capacitive electrodes, thevolume of fluid between the capacitive electrodes increases and thecapacitance reading also increases. Conversely, when the container istilted towards the opposite direction, the volume of fluid between thecapacitive electrodes decreases and the capacitance reading alsodecreases. In each occasion, tilting may be detected by comparing thecapacitance reading to the reference capacitance or the capacitancereading when the container is not tilted. The differences between thecapacitance readings may be used to determine the extent of the tilt.

Further embodiments contemplate setting a new reference capacitanceafter a predetermined period of operation of the imaging device, takinginto account the amount of fluid consumed or used during operation. Thelatest capacitance reading which is within allowable variances may alsobe saved into a memory to serve as the next reference capacitance.

Still other embodiments contemplate first and second electrode pairs onopposing sides of a housing. When one pair gives capacitance readingshigher or lower than its initial or earlier readings and the other pairgives contrarian capacitance readings lower or higher than its initialor earlier readings, respectively, tilt of the housing is made known.The extent of tilting may be also inferred based on amounts of changefrom one reading to the next.

These and other embodiments are set forth in the description below.Their advantages and features will become readily apparent to skilledartisans. The claims set forth particular limitations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification, illustrate several aspects of the present disclosure, andtogether with the description serve to explain the principles of thepresent disclosure. In the drawings:

FIG. 1 is a diagrammatic view of a fluid container having a pair ofcapacitive electrodes as in-tank sensors in accordance with the presentdisclosure;

FIG. 2 is a diagrammatic view of a fluid container of FIG. 1 showing thefluid level at zero tilt;

FIG. 3 is a diagrammatic view of a fluid container of FIG. 1 showing thefluid level when the container is tilted towards the location of thepair of capacitive electrodes by an angle θ1;

FIG. 4 is a diagrammatic view of a fluid container of FIG. 1 showing thefluid level when the container is tilted away from the location of thepair of capacitive electrodes by an angle θ2;

FIG. 5 is a diagrammatic view of a second example embodiment of a fluidcontainer having a pair of capacitive electrodes situated in a corner;

FIG. 6 is a diagrammatic view of the fluid container of FIG. 5 tilted byan angle θ3 towards the side where the pair of capacitive electrodes issituated;

FIG. 7 is a diagrammatic view of the fluid container of FIG. 5 tiltedtowards the second side by an angle θ4.

FIG. 8 is a diagrammatic view of a third example embodiment of a fluidcontainer having two pairs of capacitive electrodes situated on adjacentsides of the container.

FIGS. 9A, 9B and 9C are diagrammatic views of the fluid container ofFIG. 8 and the two pairs of capacitive electrodes tilted towards thelocation of the first pair of capacitive electrodes by an angle θ5;

FIGS. 10A, 10B and 10C are diagrammatic views of the fluid container ofFIG. 8 and the two pairs of capacitive electrodes tilted towards thelocation of the second pair of capacitive electrodes by an angle θ6;

FIG. 11 is a diagrammatic view of a fourth example embodiment of thefluid container having a pair of capacitive electrodes installed in asupport material so that the capacitive electrodes are not in directcontact with the fluid;

FIGS. 12A and 12B are first and second parts of a flow chart showing oneexample method of detecting tilting of the fluid container of FIG. 1;

FIG. 13 is a diagrammatic view of an alternate embodiment of a fluidcontainer having two pairs of capacitive electrodes situated on opposingsides;

FIG. 14 is a diagrammatic view of the fluid container of FIG. 13 tiltedtoward the location of a first pair of capacitive electrodes; and

FIG. 15 is a diagrammatic view of the fluid container of FIG. 13 tiltedtoward the location of a second, opposite pair of capacitive electrodes.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings where like numerals represent like details. Theembodiments are described in sufficient detail to enable those skilledin the art to practice the present disclosure. It is to be understoodthat other embodiments may be utilized and that process, electrical, andmechanical changes, etc., may be made without departing from the scopeof the present disclosure. The following detailed description,therefore, is not to be taken in a limiting sense and the scope of thepresent disclosure is defined only by the appended claims and theirequivalents.

With reference to FIG. 1, a container 1 to hold a volume of fluid mayinclude a housing 5 and at least one pair of opposed capacitiveelectrodes 10 a disposed on the housing 5. The fluid may be any of avariety of inks, such as those based on dye or pigmented formulations,whether water-based or solvent-based. The fluid may also typifyvarieties of color, such as cyan, magenta, yellow, black, etc. The itemmay useful in many applications such as inkjet printing, medicinaldelivery, forming circuit traces, food processing, chemicalmanufacturing, etc. The housing 5, in this example embodiment may have afirst side 15, a second side 16, a third side 17 and a fourth side 18.The at least one pair of opposed capacitive electrodes 10 a may bedisposed on the first side 15. A person skilled in the art knows thatthe housing 5 may be shaped differently and the present disclosure mayapply to fluid containers having different geometric configuration, suchas but not limited to cylindrical fluid containers and oval fluidcontainers.

FIG. 2 depicts the container 1 containing fluid at fluid level L0. Fluidlevel L0 is a fluid level at zero tilt. At fluid level L0, thecapacitive electrodes 10 a may provide a capacitance reading Frefcorresponding to the volume of fluid between the capacitive electrodes10 a. The capacitance reading Fref may become a reference capacitance.During operation, the capacitive electrodes 10 a may provide a firstcapacitance reading F1. At zero tilt and at fluid level L0, the firstcapacitance reading F1 may be approximately equal to the referencecapacitance Fref. When the container 1 is tilted at an angle θ1 towardsthe first side 15, as shown in FIG. 3, the volume of fluid between thecapacitive electrodes 10 a may increase due to a change in fluid levelfrom fluid level L0 to fluid level Lt. With the container 1 tilted andwith an increased volume of fluid between the capacitive electrodes 10a, the first capacitance reading F1 may become higher compared to thereference capacitance Fref.

FIG. 4 is a view of the fluid container 1 of FIG. 1 showing fluid levelsL0, Lt when the container 1 is tilted towards the fourth side 18 by anangle θ2. In this instance, the volume of fluid between the capacitiveelectrodes 10 a may decrease and the first capacitance reading F1 maybecome lower compared to the reference capacitance Fref. In FIGS. 3 and4, tilting of the container 1 may be detected by comparing the firstcapacitance reading F1 to the reference capacitance Fref.

FIG. 5 is a view of a second example embodiment of a fluid container 1with the pair of capacitive electrodes 10 a disposed on a portion of thefirst side 15 near the second side 16. FIG. 6 is a diagrammatic view ofthe fluid container 1 of FIG. 5 tilted by an angle θ3 towards the firstside 15 while FIG. 7 is a view of the fluid container 1 of FIG. 5 tiltedtowards the second side 16 by an angle θ4. As shown in FIGS. 6 and 7,initial and later capacitance readings from the capacitive electrodes 10a may be used to detect tilting towards the first side 15 or the secondside 16.

FIG. 8 shows a third example embodiment of the present disclosure wherea second pair of capacitive electrodes 10 b is disposed on the secondside 16 of the housing 5. In this embodiment, both pairs of capacitiveelectrodes 10 a, 10 b may be expected to provide approximately equalcapacitance readings when the container 1 is not tilted. When thecontainer 1 of FIG. 8 is tilted, as shown in FIG. 9B, the two pairs ofcapacitive electrodes 10 a, 10 b may provide capacitance readings F1A,F1B corresponding to the volume of fluid between each respective pair ofcapacitive electrodes 10 a, 10 b, as shown in FIGS. 9A and 9B. Tiltingof the container 1 may be determined based on the variance between thecapacitance readings F1A, F1B and the reference capacitance Fref.Tilting may also be determined base only on the variance between thecapacitance readings F1A and F1B. FIGS. 9A and 10A show the effect oftilting on the volume of fluid between the capacitive electrodes 10 a.FIGS. 9C and 10C show the effect of tilting on the volume of fluidbetween the capacitive electrodes 10 b.

In FIG. 11, a fourth example embodiment of the present disclosure isshown. A container 1 to hold a volume of fluid includes a housing 5, atleast one pair of capacitive electrodes 10 a disposed on the first side15 of the interior of the container 1 and a support material 25 forholding the at least one pair of capacitive electrodes 10 a. In thisembodiment, the capacitive electrodes 10 a may not be in direct contactwith the fluid in the container 1.

The support material 25 may hold the at least one pair of capacitiveelectrodes 10 a and may provide the surfaces of the capacitiveelectrodes 10 a with a cover such that there is no direct contactbetween the capacitive electrodes 10 a and the fluid. In this exampleembodiment, the possibility of any chemical reaction between thecapacitive electrodes 10 a and the fluid is small thus, the chemicalcomposition of the fluid may be preserved and the integrity of thecapacitive electrodes 10 a may not be affected. Support material 25,including the capacitive electrodes 10 a, may be also configured as amodular nosepiece that attaches to containers of various sizes. In thisway, commonality in manufacturing may exist with in-tank sensorsregardless of the size of the container to which they attach.

FIGS. 12A and 12B outline a method of detecting tilting of the container1. At the start of operation, the imaging device is turned on (100).When performing a print job, for example, the capacitive electrodes 10 amay provide a controller in the imaging device a first capacitancereading F1 (102) corresponding to the volume of fluid between the pairof capacitive electrodes 10 a. A previously-saved reference capacitanceFref may be retrieved by the controller (104). The first capacitancereading F1 may be compared to the reference capacitance Fref (106). Avariance between the first capacitance reading F1 and the referencecapacitance Fref may equate to the container 1 being tilted, however,not all variances between the capacitance readings F1 and the referencecapacitance Fref is due to tilting of the container. Variances betweenthe capacitance reading F1 and the reference capacitance Fref may alsobe caused by the vibration of the container 1 during operation. Also,not all tilting of the container 1 may cause problem during operation ofthe imaging device. Minimal tilting, such as those that may not causethe fluid to leak out of the printhead nozzles, may be consideredallowable since they do not necessitate the performance of anycorrective measures. The vibration of the container 1 and the minimaltilting, along with other factors that affect the level of fluid insidethe container 1, may be considered during the determination of acontainer tilt. Thus, the variance between the first capacitance readingF1 and the reference capacitance Fref may be compared to a previouslyset allowable positive variance X (106) and negative variance Y (108) inorder to determine whether a variance between the first capacitancereading F1 and the reference capacitance Fref is indeed caused bytilting of the container 1 and to determine if the extent of tiltingnecessitates the performance of corrective measures. Other factors thatmay be taken into consideration in determining the allowable positivevariance X and negative variance Y are the design of the imaging deviceparticularly its tolerance to tilting, the amount of fluid consumed in aprevious operation and others. Since it is already known that vibrationof the container during operation may cause a variance between the firstcapacitance reading F1 and the reference capacitance Fref, it isadvisable to obtain a second capacitance reading F2 if the variancebetween the first capacitance reading F1 and the reference capacitanceFref is outside the allowable variances X, Y. Performing a print job maybe suspended for a period of time, such as for one second (110) to allowthe fluid in the container 1 to settle so that the second capacitancereading F2 may not be affected by any vibration of the container 1.After the lapse of one second, the second capacitance reading F2 may beobtained (112). The second capacitance reading F2 may be compared to thereference capacitance Fref (114, 116) to determine whether the container1 is indeed tilted or not. When a tilt is detected and the extent oftilting is outside the allowable variances X, Y, the performance of theprinting job may be suspended and appropriate pinch valves may be closed(118) to avoid leaking of fluid in the printhead. Alternatively, a usermay be prompted to perform corrective measures. The system determines iftilt remains and the suspension of operation may be extended untilappropriate corrective measure is performed (120).

If the variance between the first capacitance reading F1 and thereference capacitance Fref is within the allowable positive variance X,the variance may be compared to the allowable negative variance Y (108).If the variance is outside the allowable negative variance Y, theperformance of the printing job may be suspended for one second (110)and similar procedure may be performed as when the variance is outsidethe allowable positive variance X. If, on the other hand, the varianceis within the allowable negative variance Y, no tilt is detected, thefirst capacitance reading F1 may be saved into the memory for use indetermining the next reference capacitance Fnref (124) and operation maybe continued (126).

In determining the new reference capacitance Fnref, the previouscapacitance reading F1 or F2, as the case may be, which is withinallowable variances X, Y, may be made as the new reference capacitanceFnref in the next cycle of operation. The new reference capacitanceFnref may also be based on the previous capacitance reading F1 or F2, asthe case may be, which is within allowable variances X, Y, and theamount of fluid consumed during a printing operation.

When tilt is detected and corrective measure is performed, thepreviously-closed pinch valves may be opened (122). When the printingjob is finished, the imaging device may be turned off (130) by the userand the appropriate pinch valves may be closed (142) to prevent fluidfrom leaking when the imaging device is tilted unintentionally during astate of non-use, such as when the imaging device is moved ortransported. On the other hand, when the printing job is finished, butthe imaging device is not turned off (130), availability of a new printjob may be determined (132). If a new print job is available, the sameprocedure for determining tilting while performing a print job may berepeated. However, if no new print job is available (132), and theimaging device is kept on (130), tilting may be determined (134). If atilt is detected (136), appropriate pinch valves may be closed (138) toavoid leaking of fluid in the printhead. A user may turn off the imagingdevice at this stage (140) to end an operation.

When a tilt is detected (136), with the appropriate pinch valves closed(138), and the imaging device not turned off (140), availability of anew print job may be determined (132). If a new print job is available(132), the entire procedure for detecting a tilt may be repeated (126).If no new print job is available (132), tilting may be monitoredcontinuously (134).

In still another embodiment, FIG. 13 depicts two pairs of capacitiveelectrodes 10 a, 10 b disposed on opposing sides of the housing 5. As isshown, a first pair of capacitive electrodes 10 a is disposed on thefirst side 15 of the housing while a second pair of capacitiveelectrodes 10 b is disposed on an opposing parallel side, e.g., thefourth side 18. When the container is not tilted, both pairs ofcapacitive electrodes 10 a, 10 b provide an initial capacitance reading.The readings may be equal to one another or not. Later, when thecontainer is tilted toward either the first side 15 as shown in FIG. 14or towards the fourth side 18 as shown on FIG. 15, the capacitancereadings of the electrodes either increase or decrease from theirinitial readings. If the reading F1A at electrode pair 10 a increaseswhile that F1B at electrode pair 10 b decreases, as in FIG. 14, it isknown that the container tilts in the forward direction toward theelectrode pair 10 a. On the other hand, if the reading F1A at electrodepair 10 a decreases while that F1B at electrode pair 10 b increases, asin FIG. 15, it is known that the container tilts in the rearwarddirection toward the electrode pair 10 b. In this way, the method ofdetermining tilt of a container varies from earlier embodiments byavoiding a need for taking a reference reading. So long as thecapacitance reading for one pair of electrodes increases while thereading for the other pair of electrodes decreases over the same periodof time, tilt of housing is made known and corrective action can betaken, if necessary. Also, an amount or extent of tilting may beascertained according to how drastic the readings vary from theirearlier readings. Amounts can be grouped according to percentage change,comparisons of raw values to other values, or by other techniques knownto skilled artisans.

The foregoing illustrates various aspects of the present disclosure. Itis not intended to be exhaustive. Rather, it is chosen to provide thebest illustration of the principles of the present disclosure and itspractical application to enable one of ordinary skill in the art toutilize the present disclosure, including its various modifications thatnaturally follow. All modifications and variations are contemplatedwithin the scope of the present disclosure as determined by the appendedclaims. Relatively apparent modifications include combining one or morefeatures of various embodiments with features of other embodiments.

1. A container to hold a volume of fluid, comprising: a housing defining an interior to retain the volume of fluid; and at least one pair of opposed electrodes disposed in the interior forming a capacitor having a capacitance that varies in response to an amount of fluid existing between the opposed electrodes, a higher said capacitance corresponds to a higher said amount of fluid existing between the opposed electrodes, wherein the at least one pair of opposed electrodes is configured to provide a first and a second capacitance measurement value to a controller configured to compare the first to the second capacitance to ascertain tilt of the housing by determining whether the second capacitance is higher than the first capacitance.
 2. The container of claim 1, wherein the at least one pair of opposed electrodes is disposed on only a first side of the interior.
 3. The container of claim 1, wherein the at least one pair of opposed electrodes is disposed vertically on a portion of a first side of the interior near a second side, the second side being adjacent and substantially transverse to the first side.
 4. The container of claim 1, further including a second pair of opposed electrodes, wherein the at least one pair of opposed electrodes are disposed on a first side of the interior and the second pair is disposed on a second side of the interior.
 5. The container of claim 4, wherein the second side is adjacent and is substantially transverse to the first side.
 6. The container of claim 4, wherein the second side is opposite the first side, the first side and the second side being substantially parallel to each other.
 7. A container to hold a volume of fluid, comprising: a housing defining an interior to retain the volume of fluid; and at least one pair of opposed electrodes disposed in the interior forming a capacitor having a capacitance that varies in response to an amount of fluid existing between the opposed electrodes, a higher said capacitance corresponds to a higher said amount of fluid existing between the opposed electrodes, wherein the at least one pair of opposed electrodes is configured to provide a first and a second capacitance measurement value to a controller configured to compare the first to the second capacitance to ascertain tilt of the housing by determining whether the second capacitance is higher than the first capacitance; wherein the at least one pair of electrodes is not in direct contact with the fluid in the interior.
 8. The container of claim 7, wherein the at least one pair of opposed electrodes is disposed on only a first side of the interior.
 9. The container of claim 7, wherein the at least one pair of opposed electrodes is disposed vertically on a portion of a first side of the interior near a second side, the second side being adjacent and substantially transverse to the first side.
 10. The container of claim 7, further including a second pair of opposed electrodes, wherein the at least one pair of opposed electrodes are disposed on a first side of the interior and the second pair is disposed on a second side of the interior.
 11. The container of claim 10, wherein the second side is adjacent and is substantially transverse to the first side.
 12. The container of claim 10, wherein the second side is opposite the first side, the first side and the second side being substantially parallel to each other. 